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In this study, combinations of two environmentally friendly compounds including a silane-based organic-inorganic coating and a rare earth (RE) salt have been investigated for mitigation of corrosion activity of mild steel. Bilayer silane coatings based on methyl triethoxy silane (MTES) and tetraethyl orthosilicate (TEOS) were reinforced by different amounts of praseodymium cations (Pr3+). The effects of Pr loading on the hydrophobicity and surface properties of the coating were studied by contact angle measurements. Fourier Transform Infrared (FT-IR) spectroscopy was done to scrutinize the curing process and possible structural changes of silane network in the presence of inhibitor. Despite the decrease in the hydrophobic nature of silane coating, the Pr cations did not change the curing of the coating. Electrochemical impedance spectroscopy (EIS) and electrochemical noise (EN) measurements confirmed the high corrosion inhibition power for the mild steel sample immersed in 400 ppm Pr containing the saline solution. The results of EIS, polarization and salt spray tests besides the scanning electron microscopy (SEM) images confirmed the silane coating healing ability and corrosion protection properties enhancement in the presence of Pr cations. [ABSTRACT FROM AUTHOR]

The current work outlines the impact of acetylacetone (AcAc) in the alkaline surface treatment bath on durability and the anti-corrosion properties of electro-galvanized steel (EGS) coated with a hybrid silane composition. The surface characteristics of the EGS samples before and after modifications were appraised using atomic force microscopy, field emission scanning electron microscopy, and contact angle measurements confirming the changes in roughness, morphology and wettability properties imposed by surface treatments. To elucidate the chemical composition of the protecting layer developed on the surface of EGS, X-ray photoelectron spectroscopy was utilized which evidently endorsed forming a film consisting of zinc hydroxide, zinc oxide, and zinc acetylacetonate. The corrosion resistance of the specimens during immersion in 3.5 % NaCl medium was determined using electrochemical impedance spectroscopy and polarization experiments. The low-frequency impedance (at 0.01 Hz) of silane-coated samples modified in the optimal condition (0.5 M NaOH bath) in the presence and absence of AcAc was respectively ca. 15,900, 5800 Ω·cm2. The electrochemical results corroborated the overriding role of a trace amount of AcAc in the corrosion protection of silane-coated EGS samples. The novel surface treatment proposed in this work provides improved corrosion protection of silane coating on EGS having the lowest i corr and presenting inhibition efficiency of 74 % in polarization experiment. [Display omitted] • Electro-galvanized steel (EGS) surface was modified by the alkaline solutions. • Silane coating was applied on the surface modified/unmodified EGS samples. • Using acetylacetone in the alkaline solution revealed a considerable impact on the corrosion resistance of silane coatings. [ABSTRACT FROM AUTHOR]

In this article, MIL-53 as (Al) metal-organic framework (MOF) was synthesized and loaded with 8-hydroxyquinoline (8HQ) as a corrosion inhibitor. The characterization based on FTIR, Raman, XRD, and XPS confirmed the successful loading of 8HQ in MOF. The corrosion inhibitive activity of the products was studied in the solution phase, single silane coating, and duplex coating system consisting of hybrid silane primer and epoxy topcoat applied on galvanized steel. XPS confirmed chemisorption of released 8HQ from the MIL-53 as (Al) on the metal surface. Electrochemical test results revealed a significant improvement in corrosion protection of single layer and duplex coating systems in the presence of 8HQ-doped MOF. [Display omitted] • MIL-53 as (Al) metal-organic framework (MOF) was synthesized. • The 8-hydroxyquinoline (8HQ) as a corrosion inhibitor was loaded in MOF. • Electrochemical techniques revealed the corrosion inhibitive activity of MOF + 8HQ. • MOF + 8HQ was included in a silane coating, top-coated by an epoxy coating. • Protection of the duplex silane-epoxy coating was improved in the presence of MOF + 8HQ. [ABSTRACT FROM AUTHOR]